This disclosure relates to lightweight, composite structures. Structures, such as space structures, utilize junctions that hold load-bearing struts together. To reduce weight, the struts and junctions may be made from polymer matrix composite materials, such as fiber-reinforced composites. However, the design of the polymer matrix composite with regard to fiber orientation and the like may not be suitable for unknown or complex load paths on the struts and junctions. The struts and junctions may therefore additionally utilize other materials, such as steel, to provide suitable strength. The steel adds weight, complicates joint design between steel components and polymer matrix composite components, and introduces compatibility issues between the different materials.